Low head dams are a killer to avoid when on the water

Posted on: July 3, 2018 | Bob Frye | Comments

This isn’t necessarily the kind of thing you’d want to admit to doing around the neighbors.

But it’s illustrative nonetheless.

Take a baby doll sometime, one with a head and body made of something firm, like plastic. Put it in your front loading washing machine and turn it on.

Watch – and listen – as that poor thing, constantly submerged, bounces and bangs around, crazily, helplessly tumbling, always at the mercy of the churning water.

Then, imagine trying to survive the same thing yourself.

You might have to if you’re a careless boater.

And good luck with that. Chances are you won’t fare any better than the doll.

Boating is surging in popularity, and right now – the Fourth of July holiday and summer in general – is when lots of people are on the water. You’ll notice crowds wherever you go.

Powerboat sales were up 6 percent in 2017, according to the National Marine Manufacturers Association. That was the sixth consecutive year of increases.

Participation in kayaking, meanwhile, about doubled between 2006 and 2015. A report done by the Outdoor Foundation and Coleman, the outdoor gear manufacturer, found that a full 7.4 percent of Americans kayaked in 2014. They took a total of 216 million trips.

Danger on the water

All of those people – as well as those in canoes, rafts and other boats – face one common danger.

It’s generally relatively small, or at least short. Often hard to spot. Found almost everywhere.

And always deadly.

We’re talking about low head dams.

Sometimes called run of the river dams, they’re also known as “drowning machines,” and with good reason.
In an article for safedam.com, Bruce Tschantz, a Tennessee-based engineer, described low head dams as concrete, brick or stone dams that run the width of an entire creek or river. They’re usually short, in that their vertical drop can be anywhere from 1 to 15 feet.

Though they are to be marked with signs or buoys, it’s often hard to see them when approaching from upstream. They sort of blend into the horizon.

Yet, for everything that seems to make them innocuous, they’re killers.

“Water flowing over a drop forms a hole or hydraulic at the base which can trap objects washing over the drop,” says Ohio’s division of state parks and watercraft. “Backwash or recirculating current is formed below the dam.

Low head dams are dangerous from upstream and down.

It’s very difficult to escape the hydraulics of low head dams.
Image: Ohio DNR

“Once swept over the dam, a victim becomes trapped and is forced underwater, pushed away from the dam, then circulated to the top. The circulating motion then repeats the cycle over and over again as the individual is drawn back against the base of the dam.”

Anyone caught in that “boil” usually faces other obstacles, too.

“To complicate matters, these dams are usually loaded with debris, such as tires and logs on the surface and rocks and steel bars just below, posing additional problems should a person get trapped in this dangerous structure,” reads a National Safe Boating Council report.

Dangers of low head dams

Low head dams kill from two directions, upstream and down

Going over one is obviously a problem. But the boil can extend as much as 100 feet downstream of the dam. Boats approaching from that direction can get caught in the current and actually be pulled upstream, until they get ultimately flip.

Either way, that’s where things get really dicey.

Your chances of survival are always better wearing a life jacket than not. But even then, it’s virtually impossible for anyone caught in that churning water to get to the surface and stay there.

It’s best not to even try.

“The best thing to do if in this situation is to tuck the chin down, draw the knees up to the chest with arms wrapped around them,” said Ohio’s watercraft division. “Hopefully, conditions will be such that the current will push the victim along the bed of the river until swept beyond the boil line and released by the hydraulic.”

The Pennsylvania Fish and Boat Commission – which produced a video years ago that included a camera-wearing mannequin going over a dam in a canoe — suggests swimming to the bottom of the river or creek and trying to crawl, crayfish-like, to the bank.

“This maneuver is very difficult, and few have done it,” though, it adds.

The chances of encountering a low head dam are pretty high. They were built all across America in the 19th century for purposes of power generation, municipal water supplies, irrigation and other reasons.

Today, thousands remain on rivers and creeks. Their original owners are long gone, so they often go unmaintained and unregulated.

Fatalities on the water

And unknowing boaters pay the price.

Tschantz wrote that 39 states have had at least one person die as a result of a low head dam.

But the problem is much larger in some places than others.

Five states – Pennsylvania, Ohio, Iowa, Minnesota and Illinois – account for almost half of the deaths over the last 50 years. Six others – Indiana, Maryland, Missouri, Tennessee, Texas and Virginia – add another 24 percent.

There’s an effort underway to get rid of a lot of these old dams, which long ago outlived their usefulness. Most recently, American Rivers, a non-profit river advocacy group, established a goal of removing 400.

That work continues, but there’s a long way to go, So, low head dams are out there, lurking.

They’re not a reason to stay home and keep the boat in the garage or shed. But they do demand respect.

That baby doll in the washing machine will show you that.

Safety tips for boating around low head dams

The Ohio Department of Natural Resources state parks and watercraft division offers the following safety tips when paddling on rivers that may contain low head dams.

  • Scout the river and know the location of hazards. Talk with boaters who are familiar with the river to gain additional knowledge.
  • Boat with experienced, responsible boaters and learn from them.
  • Watch for a smooth horizon line where the stream meets the sky. This potentially indicates the presence of a dam.
  • Look out for concrete retaining walls which are part of the dam structure and easier to spot.
  • Portage around all dams.
  • When portaging, re-enter the river at a point well downstream of the boil.

The Pennsylvania Fish and Boat Commission, meanwhile, offers a “Hazards on the water” brochure. It discusses low head dams as well as other possible dangers.

And boat-ed has an animation of how a low head dam works that’s worth checking out.

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Bob Frye is the everybodyadventures.com editor. Reach him at 412-838-5148 or bfrye@535mediallc.com. See other stories, blogs, videos and more at everybodyadventures.com.

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